The prior art, as exemplified for example by U.S. Pat. Nos. 5,263,892, 5,249,433, 4,283,922, 4,285,204, 4,336,692, 4,188,794, 4,4944,158, 4,208,884, 4,304,098, U.K. Patent 2,133,129 and Japanese Patent 54-34170, teaches that known defrost systems are complex in design, utilize electric heating elements systems which are energy consuming and costly, utilizes heat air convection systems inside the refrigerated display counter, they often require maintenance and are not very energy efficient. Furthermore, these systems are dedicated to defrost a single refrigerating coil and therefore there is a need to adapt a system to each refrigerated display counter utilizing a refrigerating coil. This is also very expensive and energy inefficient.